How to duplicate render layer
At the top of your Blender window, select Cycles Render.
In the Screen-layout drop-down, select Compositing.
At the bottom of that panel, put a check next to Use Nodes.  

You can now branch the Render Layers Image output to several nodes.
You get to decide which nodes to use.  Just Add whichever ones you need,
then send the output from your nodes to Composite Image.